Electronic devices often need to generate multiple power regimes while only being powered by a single source. For example, a laptop computer may only have a single battery but may need to produce power regimes with different supply voltages for the various components on the laptop. Furthermore, regardless of the need for multiple power regimes, electronic devices often need to condition the power that is delivered to them from an external source. Returning to the example of a laptop, the laptop processor contains sensitive electronics and exhibits a widely varying power demand based on how hard the processor is working. Simply plugging in a DC version of the mains voltage source is not an option because the processor will not be shielded from dips or surges in the power supply and the power supply will likewise not be able to keep pace with the rapid transitions in the power drawn by the processor. The aforementioned requirements are addressed by power converters.
Power converters need to adjust rapidly to changing power demands from the loads they are regulating. This feature is becoming increasingly important as one of the main ways in which power is conserved in modern electronic devices is to switch the devices between low power operating modes for extended periods of time followed by short periodic bursts in which a large amount of power is dissipated. Power converters can be classified into two broad categories referred to as switching regulators and linear regulators. In nearly every implementation of either kind of regulator, there is a control loop that monitors the output and adjusts the amount of power flowing through the regulator between the input and the output. The control loop needs to be able to sense the output and feed the information back to the regulator fast enough to prevent overshoot or undershoot of the regulated output during a transition. The range of acceptable overshoot or undershoot and the time it takes the output to settle during the transition are set by the tolerance of the device that is being regulated.